Plant Growth Regulators (Gibberellins) - PowerPoint PPT Presentation

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Plant Growth Regulators (Gibberellins)

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Discovered by Kurosawa, a Japanese Plant Pathologist in 1928. Rice plants infected by the fungus Gibberella fujikuroi showed excessive stem elongation. Symptom is called “Bakane” diseases “foolish seedling” . Chemical was extracted & purified and names as Gibberellic Acid (GA) Now 84 different Gibberellins are available – GA1 to GA84. The most commonly occurring gibberllinis is GA3 – PowerPoint PPT presentation

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Learn more at: http://du.edu.eg
Updated: 22 November 2020
Slides: 36
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Title: Plant Growth Regulators (Gibberellins)


1
Plant Growth Regulators(Gibberellins)
  • Prof. Dr./ Galal Ismail Eliwa
  • Head Of Pomology Department

Faculty Of Agriculture Damietta University
E. mail/ geliwa2002_at_du.edu.eg
2
Gibberellins
  • Gibberellins are plant hormones that promote
    growth, seed germination and leaf expansion.
  • They occur at low concentrations in vegetative
    tissues but at higher concentration in
    germinating seeds.
  • Induce cell elongation and cell division.
  • Important for plant growth and development
    through flowering and/ or seed germination.

3
Gibberellins
  • Discovered by Kurosawa, a Japanese Plant
    Pathologist in 1928.
  • Rice plants infected by the fungus Gibberella
    fujikuroi showed excessive stem elongation.
  • Symptom is called Bakane diseases foolish
    seedling .
  • Chemical was extracted purified and names as
    Gibberellic Acid (GA)
  • Now 84 different Gibberellins are available GA1
    to GA84.
  • The most commonly occurring gibberllinis is GA3

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Gibberellins
6
Gibberellins
7
Gibberellins
  • Site
  • Are produced in the shoot apex primarily in the
    leaf primordial (young leaves), roots, and
    developing seeds (developing endosperm) and
    fruits.
  • Transport
  • Made in the tissue in which it is used.
  • Transport occurs through Xylem, Phloem, or cell
    to cell.
  • Phloem seems to be most important route.
  • Transport is not polar, as it is for Auxin.

8
Gibberellins Actions
  • Promotes stem elongation
  • Stimulates cell division, cell elongation (or
    both) and controls enzyme secretions. EX dwarf
    cultivars can be treated with GA and grow to
    normal heights indicates dwarf species lack
    normal levels of GA.
  • dwarf short.,
  • wild type tall
  • dwarf GA tall
  • Thus, Ga application
  • stimulates elongation and
  • acts on intact plants.

9
Gibberellins Actions
1- Promotes stem elongation
10
Gibberellins Actions in Tissue culture
11
Gibberellins Actions in Tissue culture
12
Gibberellins Actions
  • 2- Overcomes dormancy in seeds
  • Gibberellins also have a fundamental role in
    breaking seed dormancy and stimulating
    germination.
  • The endosperm of many seeds contains protein and
    carbohydrate reserves upon which a developing
    embryo relies for energy and nutrition.
  • These reserves must be mobilized and transported
    to the embryo.
  • A range of hydrolytic and proteolysis enzymes
    break down endosperm starches and proteins into
    smaller, more easily transported molecules, such
    as sugars and amino acids.

13
Gibberellins Actions
  • Overcomes dormancy in seeds

14
Gibberellins Actions improve germination ???????
?????????? ?? ??? ???? ?????? ?????? ???? ?????
???????
15
Gibberellins Actions improving seeds germination
16
Gibberellins Actions
  • Involved in parthenocarpic fruit development

17
Gibberellins Actions
GA can induce fruit enlargment
  • Gibberellins stimulate the stalk length of
    seedless grapes to grow longer, thereby
    alleviating compaction and it promotes elongation
    of the fruit.

18
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????? ?????
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  • Gibberellins Actions improving pome fruit set
  • ????? ???? ????? ?? ????? ?????? ?????
  • ???????? ??????????
  • ??? ????? ???? ????? ??? ????? ???? ?????
    ???????? ???? ????????? ???( ?????????) ?????? ??
    5-10 ??? ?? ??????? (3-6 ??? / 600 ??? ???) ???
    ?? ??? ???? ????? ??? ???? ??????? ??? ?????
    50-75
  • ?? ?????? ?? ???? ??? ??????? ????? ???? ???
    ?????

23
Gibberellins Actions
  • Promotes cell division elongation

Red Delicious apples untreated (Left) and treated
with a combination of benzyladenine, a cytokinin,
and GA4 GA3 (Right). Note The elongated almost
pointed shape.
24
Gibberellins Actions improving pome fruit set
????? ????? ?? ??????? ???????? ??????????
  • ?? ????????? ????? 10 ??? ?? ??????? ??? 30 -
    40 ?????.
  • (1 ??? / 100 ??? ??? ???????? ?? ???? ?????
    ?????? ???? ????).

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Gibberellins Actions
  • Flowering
  • GA stimulates bolting in Long Day plants and can
    substitute for long days or cold treatments that
    are necessary for flowering.

31
Gibberellins Actions
  • Sex expression
  • In plants with separate male and female flowers,
    GA application can determine sex.
  • For example, in cucumber and spinach, GA
    treatment increases the proportion of male
    flowers for seed production.
  • In maize, GA treatment causes female flower
    development.

32
Gibberellins Actions
  • High sugar yield
  • Growing of sugarcane enhances the growth of
    internodes and increase the crop productivity
    sugar yield of crop.

33
Effect of pre-sowing seed treatment with
bio-regulators (GA3)
34
Effect of Gibberellins on fruit set and
development
35
Thank you for your attention
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